The present invention relates to capacitors in general, and more especially to a high temperature and high voltage power electronics capacitor comprising metal conductors, solid insulators/separators, and a non-reacting gas as an impregnant/dielectric. The resulting capacitor has exceptional electrical properties attributable to its unique dielectric/insulator system or package of reconstituted mica papers and non-reacting gases. The electronic circuits of today provide a variety of functions, including power factor correction, high voltage spike suppression, AC filtration, and prime sources of steady DC voltage or high power pulses.
The components and design of a capacitor are essential to its ultimate application. In simple form, a capacitor comprises at least two terminals that couple two metal conductors, which are separated and/or isolated by a dielectric component. The arrangement and the electrical properties of this dielectric will expeditiously impact the voltage rating and charge storage capability of the final capacitor. Therefore, any dielectric must have low electrical conductivity, and will usually be in the form of any combination of solids, liquids, or gases. Combinations of solid/liquid or solid/gas are typically preferred for higher voltages. Because our modern electrical and electronic systems command low-loss capacitors with higher performance prowess in terms of capacitance, operating temperatures, and energy or power densities, a suitable power electronics capacitor for these systems often employs a solid, polymeric dielectric material.
Presently, a variety of complex electronic systems are used in a host of governmental and industrial applications that could significantly benefit from the development of new elements and components, such as capacitors, which have been designed and dedicated for service in high temperature and/or harsh environments. Typical applications include, but are not limited to, the fields of space-based communications, aerospace operations, defense systems, and the exploitation of natural resources. Therein, capacitors normally require applied operating voltages of more than 1-3 kVDC, and if such capacitors were available, they would operate at temperatures in excess of 300° C., inclusive.
Current system designs either specify component isolation from these environments and potential heat sources, or they mandate the provision of cooling devices and moderating systems that will ameliorate these exposures. However, these latter designs often employ coolants, pumps, reservoirs, fittings, cabling, and/or connectors which evolve even greater volumes, higher weights, larger payload reductions, and significant costs. The resultant electronic systems often fail to reach their complete potentials due to either inadequate performance or very low efficiencies. Moreover, these systems experience larger maintenance requirements, more frequent outages, and higher costs than would be expected if a more comprehensive approach were initially taken.
In the art, Custom Electronics, Incorporated, of Oneonta, N.Y., USA, provides a commercially available power electronics capacitor with a maximum operating temperature of about 260° C. That device has operating voltage stress of about 25 volts per micrometer of thickness for its solid dielectric material (VDC/μm), a dielectric constant (ε) near 5, and an energy density of around 0.014 J/cm3. While that capacitor uses a silicone-impregnated, reconstituted mica paper dielectric, it is not deployable under the circumstances which are contemplated by the instant invention because the impregnant used therein is thermally degraded at temperatures approaching 260° C. The effect of this degradation can lead to the complete failure of most state of the art dielectrics.
These problems are solved, herein, by a new approach, which employs the adoption and deployment of materials of construction and electrical components that have been initially designed as a segment of an integral electronics component, package, or system to be subjected to harsh or high temperature environments.
It is therefore an object of this invention to provide the art with a novel power electronics capacitor, which can withstand operating temperatures in excess of 300° C., inclusive, while also maintaining a capacitance between a fraction of one to several μFs. Moreover, it is expected that the above parameters will be readily maintained at an operating voltage of about 1-3 kVDC. It is also an object herein to build this capacitor in current manufacturing facilities from commercially available materials. It is a further object that these new capacitors have sufficient shock resistance and high reliability for an extended service life.